[RFC PATCH 1/2] xen/memory : Add stats_table resource type

[Matias Ezequiel Vara Larsen <matiasevara@gmail.com>]

Allow to map vcpu stats using acquire_resource().

Signed-off-by: Matias Ezequiel Vara Larsen <matias.vara@vates.fr>
---
 xen/common/domain.c         | 42 +++++++++++++++++++++++++++++++++++++
 xen/common/memory.c         | 29 +++++++++++++++++++++++++
 xen/common/sched/core.c     |  5 +++++
 xen/include/public/memory.h |  1 +
 xen/include/xen/sched.h     |  5 +++++
 5 files changed, 82 insertions(+)

diff --git a/xen/common/domain.c b/xen/common/domain.c
index 17cc32fde3..ddd9f88874 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -132,6 +132,42 @@ static void vcpu_info_reset(struct vcpu *v)
     v->vcpu_info_mfn = INVALID_MFN;
 }
 
+static void stats_free_buffer(struct vcpu * v)
+{
+    struct page_info *pg = v->stats.pg;
+
+    if ( !pg )
+        return;
+
+    v->stats.va = NULL;
+
+    if ( v->stats.va )
+        unmap_domain_page_global(v->stats.va);
+
+    v->stats.va = NULL;
+
+    free_domheap_page(pg);
+}
+
+static int stats_alloc_buffer(struct vcpu *v)
+{
+    struct domain *d = v->domain;
+    struct page_info *pg;
+
+    pg = alloc_domheap_page(d, MEMF_no_refcount);
+
+    if ( !pg )
+        return -ENOMEM;
+
+    v->stats.va = __map_domain_page_global(pg);
+    if ( !v->stats.va )
+        return -ENOMEM;
+
+    v->stats.pg = pg;
+    clear_page(v->stats.va);
+    return 0;
+}
+
 static void vmtrace_free_buffer(struct vcpu *v)
 {
     const struct domain *d = v->domain;
@@ -203,6 +239,9 @@ static int vmtrace_alloc_buffer(struct vcpu *v)
  */
 static int vcpu_teardown(struct vcpu *v)
 {
+
+    stats_free_buffer(v);
+
     vmtrace_free_buffer(v);
 
     return 0;
@@ -269,6 +308,9 @@ struct vcpu *vcpu_create(struct domain *d, unsigned int vcpu_id)
     if ( vmtrace_alloc_buffer(v) != 0 )
         goto fail_wq;
 
+    if ( stats_alloc_buffer(v) != 0 )
+        goto fail_wq;
+
     if ( arch_vcpu_create(v) != 0 )
         goto fail_sched;
 
diff --git a/xen/common/memory.c b/xen/common/memory.c
index 297b98a562..39de6d9d05 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -1099,6 +1099,10 @@ static unsigned int resource_max_frames(const struct domain *d,
     case XENMEM_resource_vmtrace_buf:
         return d->vmtrace_size >> PAGE_SHIFT;
 
+    // WIP: to figure out the correct size of the resource
+    case XENMEM_resource_stats_table:
+        return 1;
+
     default:
         return -EOPNOTSUPP;
     }
@@ -1162,6 +1166,28 @@ static int acquire_vmtrace_buf(
     return nr_frames;
 }
 
+static int acquire_stats_table(struct domain *d,
+                                unsigned int id,
+                                unsigned int frame,
+                                unsigned int nr_frames,
+                                xen_pfn_t mfn_list[])
+{
+    const struct vcpu *v = domain_vcpu(d, id);
+    mfn_t mfn;
+
+    if ( !v )
+        return -ENOENT;
+
+    if ( !v->stats.pg )
+        return -EINVAL;
+
+    mfn = page_to_mfn(v->stats.pg);
+    mfn_list[0] = mfn_x(mfn);
+
+    printk("acquire_perf_table: id: %d, nr_frames: %d, %p, domainid: %d\n", id, nr_frames, v->stats.pg, d->domain_id);
+    return 1;
+}
+
 /*
  * Returns -errno on error, or positive in the range [1, nr_frames] on
  * success.  Returning less than nr_frames contitutes a request for a
@@ -1182,6 +1208,9 @@ static int _acquire_resource(
     case XENMEM_resource_vmtrace_buf:
         return acquire_vmtrace_buf(d, id, frame, nr_frames, mfn_list);
 
+    case XENMEM_resource_stats_table:
+        return acquire_stats_table(d, id, frame, nr_frames, mfn_list);
+
     default:
         return -EOPNOTSUPP;
     }
diff --git a/xen/common/sched/core.c b/xen/common/sched/core.c
index 8f4b1ca10d..2a8b534977 100644
--- a/xen/common/sched/core.c
+++ b/xen/common/sched/core.c
@@ -264,6 +264,7 @@ static inline void vcpu_runstate_change(
 {
     s_time_t delta;
     struct sched_unit *unit = v->sched_unit;
+    uint64_t * runstate;
 
     ASSERT(spin_is_locked(get_sched_res(v->processor)->schedule_lock));
     if ( v->runstate.state == new_state )
@@ -287,6 +288,10 @@ static inline void vcpu_runstate_change(
     }
 
     v->runstate.state = new_state;
+
+    // WIP: use a different interface
+    runstate = (uint64_t*)v->stats.va;
+    memcpy(runstate, &v->runstate.time[0], sizeof(v->runstate.time[0]));
 }
 
 void sched_guest_idle(void (*idle) (void), unsigned int cpu)
diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
index 50e73eef98..752fd0be0f 100644
--- a/xen/include/public/memory.h
+++ b/xen/include/public/memory.h
@@ -626,6 +626,7 @@ struct xen_mem_acquire_resource {
 #define XENMEM_resource_ioreq_server 0
 #define XENMEM_resource_grant_table 1
 #define XENMEM_resource_vmtrace_buf 2
+#define XENMEM_resource_stats_table 3
 
     /*
      * IN - a type-specific resource identifier, which must be zero
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 5485d08afb..bc99adea7e 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -284,6 +284,11 @@ struct vcpu
         struct page_info *pg; /* One contiguous allocation of d->vmtrace_size */
     } vmtrace;
 
+    struct {
+        struct page_info *pg;
+        void * va;
+    } stats;
+
     struct arch_vcpu arch;
 
 #ifdef CONFIG_IOREQ_SERVER
-- 
2.25.1